In medical procedures, various biopsy devices are used for taking tissue samples. Typically, a biopsy device includes a hand piece with a hollow biopsy cannula/needle, a sampling chamber, a sample separating mechanism, and a pressure generator. A portion of the hollow biopsy cannula/needle protrudes from the hand piece and is introduced into the tissue being investigated. A sample of the tissue is sucked into the sampling chamber by vacuum, separated by the sample separating mechanism, and then removed. The pressure generator, such as a pressure chamber with a single piston, generates the vacuum.
Unfortunately, large amounts of pressure can build-up within the pressure chamber of the biopsy device. The pressure build-up can decrease the efficiency and reliability of tissue extraction from the sampling chamber. Accordingly, there is the need for a biopsy device that prevents pressure build-up and provides reliable tissue extraction.